The present invention relates to a thermal printer which employs a printing ribbon coated with a thermally melting ink.
Conventionally, there is known a thermal printer which prints data such as characters, alphanumeric characters, etc., on thermal paper by means of the heating elements of a thermal head. However, thermal paper must be used as the recording medium in thermal printers of this kind. Therefore, a thermal printer which makes it possible to use ordinary paper as a recording medium has been developed, whereby a printing ribbon on which a thermally melting ink has been coated is used and the melting ink on this printing ribbon is locally fused by means of the heating elements of the thermal head, thereby transferring the image to the recording paper. In the thermal printer of this kind, both the recording paper and printing ribbon must be relatively fixed, upon printing. To satisfy this condition, a mechanism for transferring the printing ribbon is mounted on a carrier which holds the thermal head; the printing ribbon is held in contact with the recording paper through rollers; and the printing ribbon, which is so adapted as to come into contact with the recording paper when the carrier is moved, is relatively fed in the reverse direction, against the thermal head, thereby eliminating the relative movement between the recording paper and the printing ribbon. The thermal printer of this type has drawbacks, however, in that the high speed printing operation is disturbed since a number of parts are attached to the carrier, and the total weight of the carrier and various attached parts is excessive. Moreover, since printing can be done only in a single direction of movement of the carrier, movement in the other direction is only utilized for the simple return operation. Therefore, the ratio of the effective printing time is low, which results in low efficiency.